With August marking the start of peak hurricane season, forecasters are expressing even more confidence in their earlier call for a quiet period of activity.
The probability for a below-normal Atlantic season is now 90 percent, up from 70 percent in May's prediction, according to Thursday's update from the National Oceanic and Atmospheric Administration's Climate Prediction Center.
That means an expectation for six to 10 named storms -- which includes Ana, Bill and Claudette, which already developed; with one to four becoming hurricanes; and zero to one becoming major. May's call had been for six to 11 named storms, of which three to six could become hurricanes, with zero to two major. Average activity is 12 named storms, six of them hurricanes and three of them major.
Still, despite a strong El Niño making it harder for storms to form, any powerful hurricane that does develop would still be called major for a reason, said Gerry Bell, the prediction center's lead seasonal hurricane forecaster. Coastal residents "need to be prepared every year," he said.
The odds are less than normal for storms forming, "but that's the only good news," said Brian Colle, professor in Stony Brook University's School of Marine and Atmospheric Sciences, because "all it takes is one."
Also predicting a below-normal season are Colorado State University researchers who updated their outlook on Tuesday, saying this year's conditions "should combine to produce one of the quietest Atlantic hurricane seasons since 1950."
That's thanks to effects from El Niño, a climate pattern in the tropical Pacific that affects weather worldwide and leads to strong vertical wind shear in the Atlantic and Caribbean, along with enhanced atmospheric sinking, both of which suppress storm formation, the center said. Also in play this year are cooler-than-normal Atlantic sea surface temperatures.
Earlier in the spring, researchers at Stony Brook University, where a new prediction model has been developed for New York State, also made a call for below-average activity.
Hurricane season officially runs from June 1 to Nov. 30, with overall peak activity from August through October, Bell said.
Late August through the second or third week of September can be seen as peak for storms that affect the New York area, Colle said. But ongoing vigilance is needed, he said, pointing to superstorm Sandy's late October arrival in 2012.